1. Field of the Invention
This invention relates generally to an ink jet cartridge mounted in an ink jet printer for recording to a recording medium by means of ejecting ink from a recording head. The present invention particularly relates to an expulsion means for purging defective ink or bubbles associated with ink ejection problems in the ink channel.
2. Description of the Related Art
In general, an inkjet cartridge comprises a recording head unit, an ink container, or reservoir, for example a sack connecting the ink container and recording head. This ink container is typically made from a rubberized material, and under certain circumstances is unable to expel or eject sufficient ink for normal printing. This can occur when, for example an extended time the ink jet cartridge is not used for printing and the viscosity of ink around the nozzle increases from the evaporation of moisture in the ink, or bubbles form in the ink passage due to a sharp impact, such as when the cartridge is accidentally dropped.
As a means of restoring an ink jet cartridge which is unable to print normally to a condition enabling normal printing, a small hole is provided in the back of the cartridge, and the ink container or sack inside the cartridge is pressurized by a pressurizing needle provided in the printer and inserted through this small hole, thereby purging any high viscosity ink around the nozzle or bubbles in the ink passage. This type of operation is referred to as "priming" below. This type of device is discussed in, for example, JP-A-1986-249757 and JP-A-1988-274555.
Another type of recovery means, described in JP-B-1992-52782, comprises an ink tank and a priming button on a means securing the ink tank to the carriage. This ink tank provides a freely deformable ink sack for storing the ink inside the cartridge case; provides a low strength member in the component parts of the case; and provides a lever for rupturing the low strength member of the case and rotating to a position pressurizing the ink sack. The button forms a lever for rupturing the low strength member of said case, and presses the lever to prime the cartridge.
However, with the means described in JP-A-1988-274555, the back of the ink sack is pressed using a pressurizing needle. When the mount of ink remaining in the tank is great, excessive pressure may be applied, and the ink container may puncture, forming a hole. When the amount of ink remaining in the tank is low, however, the needle contacts the wall covering the opening of the ink container, and it is not possible to apply sufficient pressure to the remaining ink to adequately prime the cartridge. As a result, it is not possible to restore normal printing when the ink level is low. In addition, depending on how and where pressure is applied to the ink sack for priming, the ink sack will collapse in different ways. When the cartridge is then primed the ink sack collapses improperly, an inappropriate high negative pressure (pressure acting to return ink from the recording head to the ink sack) may remain in the ink container, possibly making it impossible to supply ink to the recording head.
With the means described in JP-B-1992-52782, there is a tendency for form burrs on the ruptured surface of the lever which may damage the ink sack. In addition, when there is little ink remaining in the ink sack, the lever must be rotated a sufficient distance in order to sufficiently prime the cartridge. This concentrates the bending stress on the pivot point of the lever, however, and can potentially break the lever. It is also necessary to increase the operating stroke of the button pressing the lever in order to rotate the lever a sufficient distance, and this factor alone increases the required size of the recovery means.